Magnetic flux distributor



Feb. 8, 1944. A. ALEssANDRl 2,341,171

MAGNETIC FLUX DISTRIBUTOR Filed my 24, .1940 2 Sheets-Sheet 1 Feb. 8, 1944. A. ALESSANDRI MAGNETIC FLUX DISTRIBUTOR Filed July 24, 1940 2 Sheets-Sheet 2 Patented Feb. 8, 1944 Alessandro Alessandri, Milan.

Italy; vested in the Alien Property Custodian Application July 24. 1940, Serial In Italy July 31, 1939 6 Claims. (Cl. 171-209) It is known that laminated members consisting of ferromagnetic sheets are used in electromagnetic apparatus and particularly in ignition masnetos for internal combustion engines to convey or distribute a variable magnetic flux. In such members it is essential to avoid the formation of short-circuit paths causing large losses due to eddy currents.

This invention is directed to members of such class in which losses by eddy currents are avoided and satisfactory conditions of operation are secured with respect both to the conveyance of magnetic flux and the machining of the parts.

This invention includes laminated members having connecting members to assemble the sheets and extending transversely to said sheets. and which are located substantially in one and the same plane parallel to the path of the magnetic flux in the member. I

On the other hand the laminated members embodied in the device and whose connecting members are in condition to provide short-circuit paths extending through several members, are

separated from each other by gaps intersecting said paths.

This invention further includes the provision of flux distributors by means of members built up in accordance with this invention which are arranged to provide sections arranged radially and longitudinally with respect to the distributor axis respectively, in satisfactory condition both as to the provision of the distributor and the distribution and conveyance of the magnetic flux.

An embodiment of this invention in a flux distributor for an ignition magneto of an internal combustion engine is shown by way of example on the annexed drawings in which:

Fig. 1 is afragmentary longitudinal section of an ignition magneto provided with a flux distributor in accordance with this invention said section being made on the section line l--l of Fig. 2:

Fig. 2 is a transverse section thereof on section line 2-2 of Fig. 1 with parts removed, and illustrates one of the distributor star members and the transverse section of the distributor core: and,

Fig. 3 is a partially schematic showing of the magnetic members with parts broken away so that a typical magnetic circuit may be followed.

In the illustrated embodiment the magneto includes a shaft I journalled in bearings 2 and 3 fast in the magneto casing l in which a stationary ring-shaped magnet 5 and a winding including a primary section I and a secondary section I are located. said winding l-i-l encircling a portion of the shaft I. Flux conveying rods 8 extend longitudinally from the poles of the magnet I and a flux distributor, as hereinafter described, co-

,operates'with said rods 8 to produce variations in the magnetic flux interlinking with the winding 6-1 to generate induced electromotive forces. A circuit breaker. not shown, actuated by the magneto shaft I, is operative in the circuit of the primary section 8 of the winding 6, l the secondary section 1 supplying high voltage to a high voltage distributor (not shown) and to cables leading from said distributor to engine sparking plugs. The breaker and high voltage distributor driven by the shaft i are not shown and may be of any approved or conventional type.

The flux distributor is fixed to the shaft l and includes a hollow cylindrical core denoted in its whole by 9 and embracing the shaft l and connected with it in rotation, said core extending throughout the winding 6, 1. The flux distributor also includes two end stars ill, Ii extending transversely beyond the ends of the winding 6, l and providing spaced arms ill, I i arranged at an angle from each other to'provide, in cooperation with the core 9 and the rods 8. the requisite magnetic paths interconnecting the poles of the magnet 5 and to cause variations in the value of the flux flowing through the core 9 and interlinking with the winding section 6 to generate an induced electromotive force.

As illustrated, each star in, ii of the flux distributor includes a head I2 of non-magnetic material which is fast with a flange 22 of the shaft 8 and a laminated ferromagnetic member l3 shaped to provide annular rim sections it", ll" each having a radially extending arm ill, ll. Each laminated member I3 is fastened on the head l2 by means of a plate It and rivets l5.

In accordance with this invention the rivets l5 embodied in each rim section and arms l0, III", II, II" are located in a plane having a diametrical location with respect to the shaft i and the whole of stars l0, II. The rim sections Ill". ll" of each star are segment shaped and are separated from each other by means of radial gaps IS in the region of said member I 3 which are included between adjacent arms. The gaps l6 also intersect the fastening plates [4.

The described arrangement prevents any shortcircuiting path in the stars ill, II because the rivets l5 of each rim section and arms ii), I0", I i, II" are located in a plane parallel with the path of the flux through the concerned rim section and arm and such paths as provided by head I I, rivets ll, laminated member II and plate I I do not intersect the flux lines extending through the concerned rim section and arm. On the other hand the gaps ll separating the several sections of each star in, II intersect such short-circuiting paths as would be provided by the rivets I! of sections as ill, l", H, H" adjacent to each other in each star iii, II. V

The assembly of the several sections of theflu distributor is provided by the fact that each section is connected by means of rivets I! to the cooperating shaft head i2.

The central core 9 of the distributor which interconnects the two stars l0; II and extends throughout the winding 6, I. is provided with longitudinal rods i1, each of which includes a laminated ferromagnetic member I! embraced by two strips i9. .Their assembly is secured by' fiat rivets 20. The ends of the rods I! enter the internal apertures provided in the rim sections H)", II" o! the stars i0, ill and said rods i! are clamped intermediate the two heads I! of the distributor.

The laminations is are parallel to each other in each longitudinal rod i1 and each rod I1 is shaped to be symmetrical with respect to a middle longitudinal plane extending through its middle line .r-a: (Fig. 2). This line, when the rod i1 is assembled in the distributor, lies in a diametrical position with respect to the axis of the shaft I.

ilgure along the rod I to the star l0 and thence toward the axis to the core rod l1. The circuit is completed through the core rod I! to star ii and thence outwardly to the adjacent rod I and back to the north pole marked N." The rotation of the flux distributor ill, 9, II when driven by the shaft I in cooperation with the magnet I and the flux conveying rods 8 causes periodical variations in the value of the flux which flows through the core rods I1 and interlinks with the primary winding section 8. The operation of the breaker inserted in the circuit of the winding section 8 generates high voltage induced electromotive forces in the winding section 1 which are supplied to the engine sparking plugs as well known.

What I claim as my invention and desire to secure by United States'Letters Patent is:

1. In an electromagnetic apparatus, a magnetic I flux distributor comprising a non-magnetic support plate, ferro-magnetic laminated members on said support plate around the center thereof and Best conditions are thus secured both in respect of machining of the rods l1 and in respect of the flow of the flux throughout the stars ill, II and rods I! because by the effect of the above described provision the edges of all the laminations it are substantially radial to the axis or the core 9 consisting of the assembly of the rods I1 and consequently they are substantially perpendicular to the tool in the lathe during machining of v 0 by the strips is and the rivets. 20 are cut by.

means of a gap 2| provided between two adjacent rods l1 and strip "(11s. 2).

The provision of the stars II, II and of the core I by means with segmental sections it, II", H, II" and I1 respectively, as above described. further secures the advantage that the flow of the iiux through the laminations of the stars II, I i and the laminations ll of rods ll of the core a is made uniform. In fact apart from the fact that the flow of the flux is uniform in respect of each rod I'I due to the substantially radial location or all the laminations ll of the concerned rod, the separation of the stars II. II in separate segmental sections it, II" and II, II" in register with several arms I0. I I causes the flux flowing through each arm l0. H to follow a radial direction in the core 9. Consequently any unevenness in the flux distribution and any flux dispersion around the core 8 as could arise from uneven gaps between the several sections l0, l0", II, II" and cooperating-rods ll of the core 9. are avoided.

A magneto equipped with the described flux distributor operates in the usual well known manner. In Fig. 3, a typical magnetic circuit is traced by a heavy broken line. This line extends from the south pole marked 8" near the bottom of t e each consisting of superimposed sheets located parallel with said plate and comprising an areshaped portion concentric with said plate and a portion extending radially from said arc-shaped portion, said members being arranged annularly around the center of said plate and being separated from each other by intervening gaps, and a plurality of connecting members assembling said sheets or each of said laminated members with each other and with said supporting plate, said connecting members being located in a plane perpendicular to said supporting plate and sheets and extending through the middle radius of said radially extending portion of the respective laminated member.

2. In an electromagnetic apparatus, a magnetic flux distributor comprising a core consisting of laminated ferromagnetic rods arranged around an axis and extending parallel with and along said axis, each of said rods consisting of sheets lying in planes substantially parallel with each other and the middle one of said sheets in said rod lying in a plane passing through said axis. connecting members assembling the sheets of each or said rods, star members each at one of the ends of said core and including a non-magnetic support plate transverse to said axis and separate ferromagnetic laminated members on said support plate, each consisting of superimposed sheets comprising an arc-shaped portion concentric with said plate and a portion extending radially from said arc-shaped p rtion. said sheets being located parallel to said plate and a plurality of connecting members assembling said sheets of each of said laminated members with each other and with said support plate, said last named connecting members being located in a plane perpendicular to said supporting plate and sheets and extending through the middle radius of said radially extending portion of the respective laminated member.

3. In an electromagnetic apparatus, a magnetic flux distributor comprising a core consisting of laminated ferromagnetic rods arranged around an axis and extending parallel with and along said axis, each of said rods consisting of sheets lying in planes substantially parallel to each other and the middle one of said sheets in said rod lying in a plane passing through said axis, connecting members assembling the sheets of each of said rods, annular star members each embracing one of the ends of said core and including a non-magnetic annular support plate transverse to said axis and separate ferromagnetic laminated members on said annular support plate and contacting with said rods, each of said laminated members consisting of superimposed sheets comprising an arc-shaped portion concentric with said plate and a portion extending radially from said arc-shaped portion, said sheets being located parallel to said plate and a plurality of connecting members assembling said sheets of each of said laminated members with each other and with said support plate, said last named connecting members being located in a plane perpendicular to said supporting plate and sheets and extending through the middle radius of said radially extending portion of the respective laminated member.

4. In an electromagnetic apparatus, a magnetic flux distributor comprising term-magnetic laminated members each comprising superimposed sheets, said members being arranged annuiarly around and extending radially from the axis of said distributor and being magnetically separated from each other by gaps and connecting members assembling said sheets of each of said members with each other, said connecting members being located in a plane extending through the middle radius of said laminated member.

5. In an electromagnetic apparatus, a magnetic flux distributor comprising a core comprising laminated ferro-magnetic rods arranged close to each other around an axis and extending parallel with and along said axis, each of said rods being separated from the adjacent rods by a gap,

and each of said rods consisting of sheets lying in planes substantially parallel with each other 'and the middle one of said sheets'in said rod lying in a plane passing through said axis and connecting members assembling said sheets of each of said rods and positioned transverse to said sheets.

6. Apparatus as described in claim 5 wherein a said connecting members are in the form of fiat rivets which extend lengthwise transversely of the sheets and which have their width dimensions extending longitudinally of the rods.

ALESSANDRO ALESSANDRI. 

